Nightly lane closures on SR 169 before month-long shutdown

Published 4:00 pm Thursday, August 6, 2026

State Route 410 will be limited to one lane at night for a week south of Black Diamond starting this Monday.

Consider this the overture to the opening scene — a month-long closure scheduled to begin later this month.

Starting Aug. 10, the stretch of highway just south of Black Diamond will be brought down to one lane from 8 p.m. to 5 a.m. through Aug. 14 to prepare for replacing three culverts that run under the road.

Flaggers will alternate traffic through the work zone each night.

A full closure of the highway will start at 12:01 a.m. Monday, Aug. 17, between Plass Road and Southeast 332nd Street, and is expected to last 35 days.

This will require commuters to use SE Green Valley Road to get around the closure.

Local access will be permitted.

WHAT IS THIS PROJECT?

There are five total culverts under SR 169, and the state is required by a 2013 court injunction to remove barriers to these culverts and hundreds of others around the state.

There are three culverts (one on Rock Creek and two other unnamed tributaries) that flow under the highway at the portion of the road being worked on this month.

Two other culverts for Ginder Creek and another unnamed tributary are under SR 169 near Roberts Drive.

2027-2028 CONSTRUCTION

Next year, commuters can expect this part of SR 169 to be closed for about 25 days at some point (an exact time is yet to be determined).

Once construction is complete outside the city of Black Diamond, work to repair culverts at the intersection of SR 169 and Black Diamond-Ravensdale Road.

At some point, all traffic will be stopped for about 60 days.

There are possible future partial or full closures later in the year.

Construction will go through 2027 until the winter, pause, and then resume the spring of 2028; again, lanes will be open until that time.

Work is expected to be complete in 2028, although construction will be affected by weather conditions and other factors.